1. Field of the Invention
The present invention relates to a frequency-doubling, amplifying surface wave receiver for a surface wave device which is formed of a material that has the piezo effect and which can be rendered electrically conductive by local doping.
2. Description of the Related Art
Known piezo electric transducers are composed of a substrate member of insulating material which exhibits the piezo effect. Two metallic contact electrodes are applied to the surface of a substrate body at predetermined intervals, and the contact electrodes are respectively connected to terminals of an alternating voltage detector. The operating mode of such an arrangement is disclosed, for example, in IEEE 1982 Ultra Sonics Symposium, pages 456 through 460, Michael J. Hoskins and Bill J. Hunsinger, "Monolithic GaAs Acoustic Charge Transport Devices".
Such a known arrangement has the disadvantage in that the amplitude of the signal voltage which is available at the two contact electrodes is small because of the low energy content of the signals which are picked-up, so that the signal must be reamplified after it has been coupled out and must be matched to corresponding, further-processing devices. Depending on the application, this may lead to difficulties. In any case, however, it leads to a relatively expensive technological outlay. Further, a harmonic of the fundamental oscillation of the surface wave element that occurs cannot be detected.